Dynamic Modeling

1. Dynamic Modeling Chapter 11 Part of Analysis Modeling Designing Concurrent, Distributed, and Real-Time Applications with UML Hassan Gomaa (2001)

2. Dynamic Modeling • Addresses the dynamic, or behavioral, aspects of a system. • Both Inter- and Intra- object interactions are considered. • Intra-object Statecharts. • Inter-object Interaction Diagrams • Produces a Dynamic Model

3. Dynamic Model • Includes: • Interaction Diagrams • Collaboration Diagrams • Sequence Diagrams • Message Sequence Description • Statechart Diagrams (if needed)

4. Overview of Dynamic Modeling • Review of Interaction Modeling • What the different types of interaction diagrams look like • How to choose which to use. • How to perform Dynamic Analysis in COMET • Determining which objects to include in the dynamic model. • Comparison of state vs. non-state oriented dynamic analysis.

5. Object Interaction Modeling • Objects and Messages are represented on an Interaction Diagram • Objects are instances of classes • Messages consist Events coupled with the data that accompanies them, or their attributes. • message = event (attributes) • e.g.: ATM Card Inserted (Card ID, Expiration Date) • Messages represent data passed from one object to another. • Messages may or may not trigger actions

6. Collaboration Diagrams • Collaboration diagrams depict messages going from one object to another. • Messages should have sequence numbers to indicate order.

7. Sequence Diagrams • Sequence Diagrams capture time sequence of interactions between objects. • Because the diagram depicts the time sequence, message sequence numbers are not necessary, but my be included. • Note that the lifelines are dashed – we do not determine object lifecycles in the analysis modeling phase.

8. Collaboration vs. Squence • Only one or the other is needed. • COMET prescribes a slight preference for collaboration diagrams. • An important part of design modeling is synthesizing the collaboration diagrams – hence collaboration diagrams must be created for all sequence diagrams anyways. • During the analysis modeling, COMET emphasizes capturing the information passed from one object to another, rather than the action taken when a message arrives.

9. What Interaction Diagrams Show • Scenarios of Use Cases • A Scenario is a particular path through a Use Case. • Alternative paths may be selected based on conditions. • Generic interaction diagrams show all scenarios. • Instance interaction diagrams show a single scenario.

10. Message Labels • Message labels take the following form: • sequence expression: message name (attributes) • Sequence Expressions may include: • Message Sequence Number • Recurrence • Iteration • Condition • Attributes are arguments, data, or parameters sent with the message • e.g.: 2.6 [Valid]: Valid PIN

11. Message Sequence Numbering • Message sequence numbers in COMET consist of: • [first optional letter sequence] [numeric sequence] [second optional letter sequence] • e.g.: • A1 • 1a • Use1.3invalid

12. Message Labeling (example)

13. Message Sequence Description • The message sequence description is a narrative describing the interactions on an interaction diagram. • Typically used to provide additional information that is not easy or appropriate to represent on the interaction diagrams.

14. Dynamic Analysis • Determines how analysis model objects interact with each other. • Begins with a Use Case • The sequence of internal interactions started by external inputs defined in a Use Case are “followed” through the system to eventual system output. • Is Iterative. • First objects associated with a use case are identified. • Then their interactions are considered and re-considered.

15. Non-State Dependent Dynamic Analysis • Determine interface object(s). • Determine internal objects. • Determine object collaboration. • Consider alternative sequences.

16. Non-State Dependent Dynamic Analysis (example) Use Case Name: View Workstation Status Actor: Factory Operator Summary: Factory operator views the status of one or more workstations Precondition: Factory operator is logged in. Description: Factory operator requests view of the status of one or more factory workstations. The request may be made on demand, or by subscription to receive notification of status changes. Alternatives: Factory workstation is down. Warning message is displayed. Postcondition: Workstation status has been displayed.

17. Non-State Dependent Dynamic Analysis (example, cont)

18. State-Dependant Dynamic Analysis • Determine Objects and Interactions. • Determine the interface object(s). • Determine the state-dependant control object(s). • Determine other internal objects. • Determine object collaboration. • Execute the Statechart. • Consider Alternative Sequences.

19. Executing the Statechart • For each state transition caused by a message, determine all the actions that result from the change in state and the objects that execute the identified actions and activities. • For each triggered or enabled object, determine the messages generated and their destinations. • Show the determined internal and external messages on both the statechart and the interaction diagram.

20. State-Dependant Dynamic Analysis (banking example) • Determine the main sequence:

21. State-Dependant Dynamic Analysis (banking example, cont) • Execute the statechart

22. State-Dependant Dynamic Analysis (banking example) • Determine Alternative Sequences

23. State-Dependant Dynamic Analysis (banking example) • Refine the statechart to include alternative sequences.

24. Summary • Dynamic Analysis determines how objects interact to accomplish Use Cases. • The Dynamic Model consists of: • Interaction Diagrams (Collaboration or Sequence) • Statechart Diagrams (if necessary) • Message Sequence Descriptions

25. Summary (cont) • Dynamic Analysis can be state or non-state dependent. • Dynamic Analysis consists of: • Determining external and internal objects. • Determining object collaborations. • Considering alternative sequences.